1. Field of Invention
The present invention relates to the LED display technology, and particularly to a high-definition LED display screen and a surface-mounted LED composite lamp with an ultra-small point distance thereof.
2. Description of Related Arts
The LED display technology has been developing rapidly these years, and LED display screens have been widely used. As society develops, the demanded display quality is becoming higher and higher, requiring the LED display definition to get improved constantly which usually needs a higher pixel density, i.e. a smaller point distance between LED pixel lamps.
In the prior art, all the LED display screens of relatively high definition use a surface-mounted LED pixel lamp (SMD LED lamp) as showed in FIGS. 1 and 2 to achieve a relatively high definition, such as, with a small point distance of 3 mm. The surface-mounted LED pixel lamp comprises a lamp body 10, a group of LED pixel lamps 11 (usually including red, green and blue LED chips) provided on the upper surface of the lamp body 10, four pins 13 provided on the lower surface of the lamp body 10, and a shading fence 12 provided around the LED pixel lamps 11. We can see from FIGS. 1 and 2 that each surface-mounted LED pixel lamp has a very small size, and yet pins 13 are usually drawn from the side face of lamp body 10 to protrude from the bottom of lamp body 10, leaving less space on the side face of lamp body 10. For a higher definition, i.e. a smaller point distance, lamp body 10 is designed with a small size almost to the limit. The surface-mounted LED pixel lamp of such a small size is difficult to pack and mount, resulting in a low mounting precision and uncontrollable rejection rate. The small size of lamp body 10 is also responsible for a limited light emitting area leading to poor color mixing performance of the LED pixel lamp. Moreover, the clearances between lamp bodies 10 are too close to use veils as a regular way to improve contrast, and even with veils mounted, it is not easy to fix them firmly on the same plane, which means the surface planeness of the LED display screen cannot be ensured. In addition, since pins 13 are thin and numerous, their alignment and arrangement on the LED light board cost so much trouble that it's difficult to improve the brightness and refresh rate of the LED display screen. All these problems have seriously affected the display quality of the high-definition LED display screen and hampered its development and application. Therefore, the prior art requires betterment.